| 摘要 |
PURPOSE:To improve tear resistance to make a slit workable more easily and level off coarse large protrusions on the surface to restrict a dropout when a magnetic tape is made by determining the ratio of the lamination thickness of polyester containing ethyleneterephthalate as a main constituent and the entire thickness of a laminated film to be 1/100 to 1/5. CONSTITUTION:A biaxially oriented laminated polyester film is a laminated film consisting of polyester containing ethyleneterephthalate as a main constituent laminated on at least, one surface of polyester containing ethyleneterephthlate as main constituent. The required lamination ratio is 1/100 to 1/5 for the thickness of the ester layer based on ethylene terephthalate as a main constituent to the entire thickness of the laminated film, and preferably 1/75 to 1/7. Polyester A is laminated on one surface or polyester B, then a 2 to 3-tier sheet is extruded from a slit-like mouthpiece and is cooled using a casting roll to prepare an unstretched film. |
